A conventional circuit breaker uses a fuse between a switch and a circuit so that when electrical overloading occurs, the fuse melts off first before the overloading causes damage to the circuit. However, if the fuse is not properly installed or an improper fuse is used, the overloading current does not melt the fuse and a disaster can occur. U.S. Pat. Nos. 5,262,748, 4,167,720, 4,937,548, 5,223,813, 5,451,729, and 5,558,211 disclose different types of circuit breakers which commonly include a complicated mechanism to drive the bimetallic plate that is expected to be deformed and bent when overloading occurs. Nevertheless, it is noted that in some cases, even when an overloading occurs, the bimetallic plate does not completely deform as desired and remains in contact with a terminal of the circuit so that sparks could be produced, causing disaster.
Therefore, it is desired to have a mechanism that ensures the bimetallic plate to be deformed as desired and designed so that the circuit is completely cut off.